steam not going to two radiators

Snowmelt

was called to a job 2 rads where not getting warm ( tenement said didn't get hot for 6 years ) . one is in kitchen other was in another room being kitchen. Both rads where on main steam line. What I noticed was that the steam line was sagging a little. Other thing I noticed was that there was no steam vent on the particle run that had no steam. third thing was that the shut off and steam bleeders at the rads where just disgusting and no handle to turn on or off so I couldn't eve n tell if it was working .
final flaw I saw was a drain valve on bottom off hardford loop was clogged where no water could get out.
one question that i have is will a pitched pipe cause steam not to make it up the pipe ?
2nd question is would a clogged wet return stop the steam from getting to the end of the run in a timely matter?
I know I should install a main steam vent on the main where none exist .
I know I should replace thew steam vents on rads and shut offs
anything else I miss?

Fred

If the pipe is pitched the wrong way, or if there is a sag in the pipe it will fill with condensate and prevent steam from getting to the radiator.
The clogged wet return won't block steam from getting to the Radiator since the wet return is already below the boiler water line (or should be). It is very possible the wet return is clogged enough to slow or block water from getting back to the boiler but that's a different issue.

Snowmelt

Fred your statement makes perfect sense but I am afraid I don't think that is happening ( when it pitches back down it down to the end of the bent ( about 8 feet ) then it goes to the return which is low to the ground, so any water that might accumulate in there is actually going to drop back into the system.

Fred

If pitch isn't the issue, then one of the following likely will be:
- Lack of main venting prevents steam getting to those radiators before the thermostat is satisfied, in another room.
- pipe sag where water is pooled causing steam to condense before it gets to the radiator
- Lack of pipe insulation, especially in a crawl space causing steam to condense before reaching radiator.
- Radiator valve not fully open
- Radiator vent stuck closed, not letting air escape from feed pipe and/or radiator.
- rarely but maybe a boiler undersized enough that the mains, run-outs and radiators will not fill.

I'm betting on main venting as the first culprit.

Snowmelt

fred that's what I am betting on also. I will re-post after I fix this next week or two.

Snowmelt

Fred I did the job, 2 rads where clogged to the point where the customer said just get new ones, also the pitch made it impossible for the steam to get to the one rad, but I did install a main air vent on one side of the run and replace the existing one with a new vent, also changed a few shut off that wherent working properly.

Fred

Glad you got it fixed!